The present invention relates to protective coverings which are utilized for covering structural components or units of the machines, for example cutting machine tools so as to protect people passing thereby against injuries by metal components.
The structural elements covered with protective coverings are also protected against harmful effects and the personnel is protected against possible dangerous contact with those structural elements and units of the machine. These protective coverings can be employed, for example, with the machine tools for forming workpieces by cutting, for covering, for example such structural elements as slide or guide tracks, or shafts, or spindles. These protective coverings may be, for example foldable bellows or aprons. The length of such coverings is variable, so that a covering connecting two spaced machine parts, displaceable relative to each other, covers the space between these parts as well as structural elements, as slide or guide tracks, within that space. These protective coverings are foldable and expandable like harmonika. The protective coverings, which, for example are applied to cutting machine tools or processing centers, can be exposed to actions and attacks by hot metal chips as well as to attacks by cooling and lubrication agents. In these instances the protective coverings are provided, in the region of the direct attacks of the above agents, with covers made of metal laminations resp. lamellae or sheets overlapping each other in a squamous fashion.
The present invention relates more particularly to a protective covering for structural components of the machines, which includes a foldable support and a cover provided on the outer side of the support and comprised of a plurality of laminations overlapping each other in a squamous fashion.
For connecting the individual laminations of the cover with the foldable support there are many possibilities.
In the protective covering disclosed in DE-Gbm No. 7,809,596 and including a cover and a foldable support formed of foldable bellows the individual laminations or sheets of said cover have an angular profile. Each individual sheet of the cover is rigidly secured immediately to the angular arm on the fold wall of the support, for example by gluing to the fold support. This fastening of the angle-shaped laminations has the disadvantage that, upon the folding of the folds of the support of the protective cover to a folded position the laminations can raise so that the cover can expand. Thereby interstices between individual laminations will occur so that the screening of the upper surface of the foldable bellows will be no longer ensured. The closest possible arrangement of the individual folds of the support with one another is substantially determined and limited by the thickness of the laminations in the region of glue connections between the laminations and the fold walls of the support. Moreover, in many machine tools the space given for installing the protective covering is limited so that there is a requirement that the protective covering having a predetermined maximal length of extension would be able to be pressed to a possible smallest overall dimension, so-called block dimension. In the protective covering pressed to a so-called block dimension, the folds of the carrier or support lie closely adjacent to each other. With special inserts, where the protective covering is exposed to special lubricating and cooling agents it has been however, observed that adhesive connections in the protective coverings had no sufficient service life and durability. The adhesive connections made with usual adhesives or glues employed for securing the laminations to the foldable support have not been universal and could not be applied in each case.
Another known protective covering, disclosed in DE-Gbm No. 7,904,162 includes a cover and a foldable bellows as carrier of the lamellae or sheets of the cover. At every second upper fold peak of the bellows projects a connection member, so-called welt which extends over the lengths of the fold peaks and is secured thereto. This welt includes a web portion and a thicker head portion. The web portion, is inserted into a portion in the fold peak. The head portion of the connection member extends parallel to the edge of the fold peak. To connect a sheet or lamination to a connection member the head portion of this member is inserted into a clamp-shaped connecting portion on the longitudinal side of the lamination, for example from the side thereof, and is clamped in the end portion of the lamination. The clamp-shaped end portion of each lamination is arranged on the bent or arm-like portion thereof. With this releasable connection with the aid of the connection members the above noted difficulties, occuring when adhesives are employed, are avoided. The mounting of the connection member or so-called welt and the forming of the clamp-shaped end portions of the laminations for receiving the head portion of the connection member are, however rather complex. Furthermore with such construction of the protective covering, practically no movability is given to the laminations relative to the support. It is also difficult to position the folds of the support and, respectively the laminations, closely adjacent to each other or to obtain a required block-or-overall dimension. The possible smallest block dimension provides the possible smallest space consumption in the folded position of the protective covering with a predetermined maximal length of expansion. Inasmuch as the space available for protective coverings for compact machine tools is always small the small block dimension with the maximal length of expansion of the covering becomes an important criteria.